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About

History, Innovations and Technical Highlights


Thermal Equipment Corporation was incorporated in 1970 as an outgrowth of Fuel Engineering Corporation, the pioneer autoclave manufacturer in the United States since the 1950s. After the purchase of Baron Autoclaves (as well as Baron Blakeslee Degreasers) in the late 1980s, TEC became the world’s largest manufacturer of composite bonding Autoclaves for the aerospace and defense industries. TEC has built up to 70% of all aerospace autoclaves purchased world-wide.

Many of TEC's managers, engineers and technicians have been with the company upwards of 20 years, and we are continuing the legacy with new interns in every department. TEC Autoclave Systems are known for their robustness, quality and reliability that perform well in heavy production environments over long periods of time. Our unparalleled level of experience, quality workmanship and concern for system performance have made TEC the recognized leader in the Aerospace Autoclave industry. This high level of performance is due to the experience and over-engineering of key components such as the closure design, hinge design, door bolt, encapsulated fan motors, heating and cooling coils, our methods of internal sheet metal installation, and other engineering and manufacturing processes that have been pioneered by FECO and TEC over the last 50 years.

Autoclave Construction

Innovations & Highlights


  1. Over Engineered Door Systems
  2. All TEC Door Systems are designed to prevent deformation, rather than simply designed around allowable stresses, in order to ensure reliability and improve the life of the door in a Production Environment. The oversized hinge assemblies incorporate Oilite bushings for zero maintenance and exceptional performance for the life of the Autoclave. The actual closure and wedges are also oversized to reduce stress levels and ensure long life.
  1. High Quality Gas Fired Combustion Systems
  2. TEC’s Indirect Gas Fired Combustion Systems include 321SS materials to hold up to the high temperatures, and most importantly, to the corrosivity of the process heat created by the acidic atmosphere inherent in a combustion system. 304SS will not hold up to the corrosivity for nearly as long as 321SS material. TEC’s Heating Coils are also engineered to include 20% excess capacity and are assembled to last decades with out the need of removing the Coil for servicing.
  1. Standardized Blower Design
  2. TEC supplies both a Combustion Blower and a Mass Air Blower as part of our standard Combustion Systems. This provides a more flexible system for ease of tuning, helps to facilitate lower emissions, and efficiently moves the heated air into the Autoclave Heating Coil at temperatures up to 1,500 degrees F.
  1. Completely uniform Heating
  2. All TEC Autoclaves include a radial air annulus to properly provide the Autoclave working space uniform heated air, at the proper velocity (typically 200-300 fpm, as specified by the customer). TEC engineering sizes the Main Autoclave Fan Motor based on the theoretical thermal load and the requested velocity.
  1. Fisher Control Valves
  2. TEC only uses Fisher proportional control valves on the Pressurization Valve, Vent Valve, Vacuum Control Valves and Main Cooling Valve. Fisher’s products has proven to be the industry leader in proportional control, helping in utility utilization and efficiency.
  1. Allen Bradley Control Systems
  2. TEC has standardized on Allen Bradley (AB) PLCs and Touch-Screens which have proven to be the most reliable product on the market for Autoclave control. TEC has also standardized on Agilent Data Acquisition Units, separate from the PLCs to ensure reliability.
  1. Removable Vacuum Pass-Throughs
  2. TEC’s vacuum pass-throughs are removable, allowing for convenient maintenance and repair of vacuum lines.
  1. Encapsulated Autoclave Fan Motors
  2. TEC was one of the first manufactures to use a fan motor that is internal to the pressure envelope of the Autoclave vessel. The original implementation was to install the motor physically inside the Autoclave with access via a blind flange on the back of the Autoclave. While this worked reasonably well, maintenance proved to be difficult. The innovation by TEC was to use an external motor housing that was at the same pressure as the Autoclave, which provided significantly easier access to the fan motor while reducing the temperature it was subjected to.
  1. Replaceable Sleeved Motor Housing Cooling Coils
  2. Due to the ASME requirements for pressure vessels, any repairs or alterations of the main Autoclave vessel, once it has received ASME certification, require re-inspection and the filing of an ASME “R1” repair report. This process causes delays and additional cost. TEC’s innovative solution was to install sleeves in the motor housing head, which moves the welding of the motor housing cooling coil away from the main pressure vessel, and provides easier replacement of the coil without requiring any ASME paper work or inspections.
  1. Autoclave Door Bolt Safety Locks
  2. Although required by ASME code, the design of the Door Bolt devices varies greatly between Autoclave manufacturers. TEC has developed a very robust design that not only satisfies the basic ASME requirements, but also adds an additional margin of safety. In addition to this superior design, TEC incorporates not one, but two electrical interlock switches on all large Autoclave Door systems. And TEC’s interlock air cylinder uses a custom low pressure spring to insure the cylinder engages at the lowest pressure possible, while still providing reliable operation.
  1. Alarm Wiring and Detection with PLC Logic
  2. TEC pioneered a “proof of signal” on all critical alarms. We must have a positive signal to indicate that the condition is okay, which proves the alarm wiring and switches are functioning correctly. A loss of signal will then indicate an alarm condition.
  1. Special Cooling Coils
  2. TEC has developed a special design for all cooling coil tube sheets to allow for expansion and contraction during heating and cooling. TEC cooling coils also have a slight slope to insure self-draining to prevent corrosion in the coils.
  1. Proprietary Sheet Metal Installation
  2. TEC uses a proprietary method of installing all Autoclave vessel internal sheet metal to insure long term reliability and to reduce buckling due to thermal expansion. The pegs and bands are designed to reduce heat conductivity to the pressure vessel shell by using a smaller 1 1/2 inch band with pegs welded to the shell. High operating temperature TEC Autoclaves also have a notch cut in the shell side to further reduce conductivity and have special heavy duty foil to reduce heat convection through the insulation layers. TEC also uses special insulation techniques to insure staggered seams.
  1. Door Flange Cooling
  2. TEC pioneered the use of flange seal cooling on both the door and shell flanges to reduce temperature, insuring reliable operation of the closure after sustained high temperature operation. The feature is implemented in all TEC Autoclaves designed for operation at 650F or higher. The cooling circuit goes through the vessel shell and is routed close to the parting line. The cooling tubes are held in place by square bars with the cavity filled with heat conductive putty prior to installing the cover plates.
  1. Part Thermocouple Jack Panel Boxes
  2. TEC determined that air penetration along the vessel shell was causing accuracy errors with the thermocouple jack panels. This airflow was exiting at the pass-through assembly, which cooled the back of the jack panels. The jack panels must be within 100° F front to back to provide accurate readings, so to resolve this issue, TEC installs the jack panels in a sheet metal box which keeps the temperature at the back nearly the same as the front.
  1. Autoclave Interior Lighting
  2. TEC pioneered the first interior lights that provided reliable operation. Testing and research determined that a pressurized halogen bulb would be required to survive the harsh conditions of a pressurized Autoclave. TEC then designed a suitable housing using high temperature sockets and wiring.
  1. Internal Autoclave Camera Systems
  2. TEC pioneered the use of video cameras and recording systems to document the internal events during an Autoclave cure cycle. We use a quartz lens assembly suitable for the pressure of the Autoclave and provide a water cooled flange to reduce the lens and shell temperatures. The camera housing is designed to provide easy access to the camera while providing explosion protection in the event of a lens failure.
  1. Ultra High Temperature Autoclaves (1,500° F)
  2. TEC has developed several specific enhancements used for ultra high temperature applications, including a nitrogen purge for the motor housing. This insures a constant airflow from the motor housing to the internal Autoclave work space to reduce fan motor temperatures.
  3. We also developed a special cocoon style insulation technique that maintains a slight clearance between the insulation and the vessel shell, which utilizes a nitrogen purge at several locations on the shell. The helps reduce external vessel shell temperatures and the amount of insulation required.
  1. Rear Head Assemblies to improve Efficiency
  2. TEC pioneered the use of seal welding on all Autoclave rear head sheet metal. As this is the high pressure zone for the fan system, we determined that the air loss through the seams on this sheet metal was detrimental to the system efficiency. This unwanted airflow also contributed to the problems seen with the inaccuracy of part thermocouples.
  1. “Autoclave Computer Control System” (ACCS) Software
  2. TEC was the first Autoclave System manufacturer to offer complete computer control utilizing part feedback. Our ACCS software was completely designed and written by an in-house software team based on the input from customers.
  3. ACCS is a complete control and data acquisition system for the processing of composite materials in Autoclaves, Ovens and Presses. The system may be installed on existing or new process equipment, and features include part data logging, and control by rate, threshold pressure, tool, and serial number. Complete interactive operator display with graphics and prompting is included, and report generation is available in Summary, Graphical, and Detailed formats. Also included are a Customer computer interface cure cycle storage library and cycle data archiving on a CD drive, tape or the customer’s network.
  1. Vacuum Valve Assemblies
  2. TEC developed the first self contained resin trap with internal filtration. These are intended mainly to act as a separator to collect resins, alcohol and water. Their efficiency can be increased by using a chilled water system.
  1. Pioneered Vacuum Manifold Valves
  2. TEC pioneered the first self contained vacuum valve assembly to allow the use of partial or full vacuum to a bagged part. The valves could be readily cleaned and rebuilt from the front of the control panel without the need to be removed. These valves have since been replaced with more sophisticated vacuum systems.
  1. Shuttle Valve Assemblies with Automatic Calibration
  2. TEC was the first Autoclave System manufacturer to design custom shuttle valves that offer automatic calibration. These assemblies were electrically controlled and allowed switching the desired transducer from “Read” to “Calibration” and from “Source” to “Vent”, completely by the computer.
  1. Horizontal Split Autoclave
  2. As part of TEC’s continued efforts to support Customers with specific application equipment, we designed and fabricated the world’s only horizontally split Autoclave System, fitted with a heated platen in the lower section.
  1. Originally Designed Custom Electronics
  2. TEC was at the leading edge of Autoclave automation and designed and engineered many of the specific electronics required for our state of the art control systems. These items were custom fabricated to TEC’s specifications and included part vacuum transducers, Autoclave pressure transducers, signal splitters and zero-span networks. TEC also designed and fabricated the world’s first IEEE-488 transfer box. No other Autoclave manufacturer could provide this type of transfer box which was critical to our ACCS redundant computer systems. The transfer box was used to transfer the communications of two computers to various devices, including printers and relay boards. And TEC was the first to incorporate computer controlled vacuum valve assemblies by modifying relay boards to meet our needs.
  1. Extensive Field Fabrication Experience
  2. TEC’s extensive experience with large field fabrication projects over the years have taught us how to work in close coordination with our Customer’s other contractors, required to complete the install, the hook-up of all utilities, etc., in an orderly fashion to help minimize any impact to the schedule.
  1. Quick and Knowledgeable Service
  2. TEC’s Customers enjoy the benefits of a knowledgeable and fast acting phone / field services. Our elite group of Preferred Customers that request service on their Autoclaves are acknowledged within 24 hours and if required, an expeditious service plan is prepared and implemented within 48 hours (coast to coast).